1. Field of the Invention
The present invention is generally directed toward receiver-transmitter systems referred to as Family Radio Service (FRS) units, although the invention is not limited to this embodiment. The Family Radio Service (FRS) is one of the Citizens Band Radio Services. It is intended for the use of family, friends, and associates to communicate among themselves within a neighborhood or while on group outings. There are fourteen discreet FRS channels available for use on a “take turns” basis. The FRS unit channel frequencies are:
Channel No.(MHz)1462.56252462.58753462.61254462.63755462.66256462.68757462.71258467.56259467.587510467.612511467.637512467.662513467.687514467.7125Other selected technical specifications are:
(a) Frequency modulation (although phase modulation is allowed);
(b) Frequency tolerance of each FRS unit must be maintained within 0.00025%;
(c) The authorized bandwidth for an FRS unit is 12.5 KHz; and
(d) Effective radiated power (ERP) shall not, under any condition of modulation, exceed 0.500 W.
The operating rules for the FRS are found at 47 C.F.R. 95.191–95.194. For additional technical information, see 47 C.F.R. 95.601–95.669.
2. Related Art
A variety of FRS systems are available. Presently available FRS systems do not directly down-convert FM signals to demodulated baseband information signals.
What is needed is a method and system for directly down-converting FM signals to demodulated baseband information signals.